LGA 1156

LGA 1156. Also known as Socket H, it is a land grid array CPU socket designed by Intel Corporation for its Nehalem and subsequent Westmere microarchitecture-based desktop and entry-level server processors. Introduced in September 2009, it marked a significant architectural shift by integrating key components like the memory controller and PCI Express controller directly onto the processor die, moving away from the traditional northbridge-centric design. This socket was a cornerstone for Intel's mainstream platform, supporting the initial wave of Core i7, Core i5, and Core i3 branded processors, before being succeeded by the LGA 1155 platform.

Overview

The LGA 1156 socket was launched as part of Intel's "Tick-Tock" strategy, representing a major "Tock" architectural update. It debuted alongside the Lynnfield and Clarkdale processor cores, which brought the Nehalem architecture to the mainstream market. A key innovation was the relocation of the memory controller and a PCI Express 2.0 controller from the chipset to the CPU itself, significantly reducing memory latency. This architectural change necessitated a new socket and new supporting 5 Series chipsets, such as the P55, which acted more as a centralized I/O hub. The platform competed directly with AMD's contemporary Socket AM3 offerings.

Technical specifications

The LGA 1156 socket features 1156 protruding pins that make contact with pads on the underside of the processor. It supports processors with a TDP of up to 95 watts for mainstream quad-core models. The primary interconnect between the CPU and the chipset is the DMI, a serial link replacing the older Front-Side Bus. For communication in multi-socket configurations, some server-oriented LGA 1156 Xeon processors utilized the QPI protocol. The integrated memory controller supports dual-channel DDR3 memory, and the on-die PCI Express controller provides 16 lanes of PCIe 2.0 connectivity directly from the CPU.

Supported processors

LGA 1156 supports a range of processors based on the 45 nm Nehalem and 32 nm Westmere microarchitectures. The initial flagship desktop CPUs were the Lynnfield-based Core i7-800 and Core i5-700 series. This was followed by Clarkdale processors, which were dual-core dies with an integrated Graphics Media Accelerator (GMA) on the same package, including the Core i3-500 series, Pentium G6000 series, and Celeron G1000 series. The socket also accommodated select Xeon processors, such as the Xeon 3400 series, for entry-level uniprocessor servers.

Compatible chipsets

The platform was supported by Intel's 5 Series family of chipsets, codenamed Ibex Peak. The mainstream flagship was the P55, designed for Lynnfield processors without integrated graphics. For systems using Clarkdale CPUs with integrated graphics, chipsets like the H55, H57, and Q57 were required to provide display output connectivity. The P57 was a planned variant that was ultimately canceled. For the server segment, the Intel 3420 chipset provided support for Xeon 3400 series processors.

Motherboard designs

Motherboards for LGA 1156 were produced by all major manufacturers, including ASUS, Gigabyte, MSI, and ASRock. Designs ranged from basic ATX and microATX boards for office and home use to high-end models aimed at enthusiasts, often featuring robust power delivery systems and support for SLI or CrossFireX multi-GPU configurations. The relocation of core functions to the CPU allowed for simpler motherboard layouts compared to the preceding LGA 775 platform, though board designs were distinctly different from the subsequent LGA 1155 due to incompatible pinouts and power requirements.

Successor and market position

LGA 1156 had a relatively short market lifespan, being replaced in early 2011 by the LGA 1155 socket and the accompanying 6 Series chipsets supporting the new Sandy Bridge microarchitecture. The successor platform offered improved performance, a more advanced integrated graphics solution, and the introduction of technologies like Smart Response Technology. While LGA 1156 was a pivotal transition platform that successfully brought key Nehalem innovations to the mainstream, its rapid replacement by LGA 1155 limited its long-term upgrade path and cemented its role as a technological bridge between older architectures and the modern Core processor era. Category:CPU sockets Category:Intel microprocessors Category:Computer hardware standards